A plurality of optical repeaters are provided on a transmission line between an optical transmitting station and an optical receiving station. A combined transmission line section is provided between optical repeaters. The combined transmission line section is composed of the first optical fiber, which is a positive-dispersion fiber, and the second optical fiber, which is a negative-dispersion fiber. Signal light is inputted to the first optical fiber in each combined transmission line section. Each optical repeater inputs pump light to the second optical fiber.